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Drugs Acting On Calcium Metabolism

  • Abnormalities in bone mineral homeostasis can lead to a wide variety of cellular dysfunctions (e.g. tetany, coma, muscle weakness), and to disturbances in structural support of the body (e.g., osteoporosis with fractures) and loss of hematopoietic capacity (e.g., infantile osteopetrosis)
  • Three hormones serve as the principal regulators of calcium and phosphate homeostasis: parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), and vitamin D.
  pth vitamin d fgf23
Increased calcium and phosphate absorption (by increased 1,25(OH)2D production) Increased calcium and phosphate absorption by 1,25(OH)2D Decreased calcium and phosphate absorption by decreased 1,25(OH)2 production
Decreased calcium excretion, increased phosphate excretion Calcium and phosphate excretion may be decreased by 25(OH)D and 1,25(OH)2D Increased phosphate excretion
Bone Calcium and phosphate resorption increased by high doses. Low doses may increase bone formation. Increased calcium and phosphate resorption by 1,25(OH)2D; bone formation may be increased by 1,25(OH)2D and 24,25(OH)2D Decreased mineralization due to hypophosphatemia and low 1,25(OH)2D levels, but may have a direct action on bone as well.
Net effect on serum levels Serum calcium increased, serum phosphate decreased Serum calcium and phosphate both increased Decreased serum phosphate
  1. Parathyroid hormone
    1. PTH is peptide and 1-34 sequence is used in osteoprosis.
    2. Teripartide is a synthetic PTH analogue used in osteoporosis.
    3. Stimulates bone matrix. The drug is avoided in patients with bone malignancies, as it can exacerebate them.
    4. Hypercalcemia is a side effect.


  1. Denosumab Humanized antibody which is RANKL analogue and is used in osteoprosis.  


  1. Cinacalcet Ligand of calcium sensing receptor. This decreases parathyroid hormone levels. Used in secondary hyperparathyroidism seen in chronic renal failure. 
  2. Raloxifen This is a SERM and is used in postmenopausal osteoprosis. Side effect is vascular thrombosis. Therefore, the drug is avoided in deep vein thrombosis. 
  3. Tibolone Newer SERM and is used to treat postmenopausal symptoms. Also used for treatment of postmenopausal osteoporosis. 
  4. Bisphosphonates These are pyrophosphate compounds.


  • These act by increasing the activity of osteoblasts and reducing the activity of osteoclasts. These have been shown to reduce both vertebral and non vertebral fractures.


  1. These have poor oral bioavailability.
  2. All of them are long acting drugs and are not metabolized in body.
  3. These are eliminated unchanged by body. Hence are contraindicated in renal failure.
  4. Side effects include reflux esophagitis. This can be prevented by asking the patient not to lie down after taking the drug.
  5. Once develops, it could be treated by proton pump inhibitors.
  6. Osteonecrosis of jaw has been reported as its side effect. Bone, muscle, joint pain and fatigue are side effects of these drugs.

Individual Drugs

  1. Alendronate is most commonly used and is given weekly.
  2. Ibandronate can be given once a month. Panidronate, tiludronate, risedronate are other drugs.
  3. Zolindronic acid is the longest one which can even be given on early basis. 
  1. Plicamycin
    1. Plicamycin is a cytotoxic antibiotic that has been used clinically for two disorders of bone mineral metabolism: Paget’s disease and hypercalcemia.
  2. Strontium Ranelate
    1. Strontium ranelate is composed of two atoms of strontium bound to an organic ion, ranelic acid.
    2. Strontium ranelate appears to block differentiation of osteoclasts while promoting their apoptosis, thus inhibiting bone resorption. At the same time, strontium ranelate appears to promote bone formation.
    3. Unlike bisphosphonates, denosumab, or teriparatide, this drug increases bone formation markers while inhibiting bone resorption markers. Large clinical trials have demonstrated its efficacy in increasing bone mineral density and decreasing fractures in the spine and hip. Toxicities reported thus far are similar to placebo.
  3. Fluoride: Fluoride accumulates in bones and teeth, where it may stabilize the hydroxyapatite crystal.
    1. Fluoride in drinking water appears to be most effective in preventing dental caries if consumed before the eruption of the permanent teeth. The optimum concentration in drinking water supplies is 0.5–1 ppm. Topical application is most effective if done just as the teeth erupt.
  4. Gallium Nitrate: approved by the FDA for the management of hypercalcemia of malignancy.
    1. This drug inhibits bone resorption.
    2. Because of potential nephrotoxicity, patients should be well hydrated and have good renal output before starting the infusion.
  5. Calcitonin
    1. Hormone produced by parafollicular C cells of thyroid gland. This is 32 amino acid peptide and is a calcium lowering hormone. It is coupled to G protein coupled receptors.


The drug inhibits osteoclastic activation.

The drug is given via inhalational route and is obtained from salmone.

  1. It is given as a nasal spray of 200 IU/day.  It is a short acting drug with a half life of few minutes.


  1. It is the drug of choice for:
    1. Bone pain and hypercalcemia of malignancy.            
    2. Paget’s disease
    3. Postmenopausal osteoporosis.                          
    4. The drug can also prevent fractures.


  1. Side effects include flu like symptoms other systemic features. 

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